Self-locking nut



, J. H. ROBERTSON 2527,93

SELF-LOCKING NUT Filed Sept. 5, 1939 Patented Mar. 10, 1942 I UNITED STATES PATENT OFFICE 2,275,993 SELF-LOCKING NUT John Hogg Robertson, London, England Application September 5, 1939, Serial No. 293,499

- In Great Britain September 6, 1938 3 Claims. (Cl. 151-25) This invention relates to self-locking nuts of to the cone-frustum by a. suitable die after the with the thread of the bolt. wall against upward movement of the spring e invention has for its object the provision member.

of a self-locking nut with progressive and non- The screw thread of the bolt 6 pr res lv wedging locking action which is capable of freengages the four chord-like arms of the spring only. standard tools are required. io'with each arm being approximately midway of The invention is hereafter described with iefthe length of the arm between adjacent corners erence to the annexed drawing, in which or angles. The only surfaces which apart from Fig 1 1s a plan View and Fig 2 1s a side elehe normal screw thread, frictionally engage vation of the improved self-locking nut. Figs. 3 with the bolt thread are those which are in tenand 4 are sectional elevations on lines 3-3 and sion and spring-urged the points which have 44 of Fig. 1, respectively, the bolt being shown the substantial support of the wall of the crown b in Fig. 4. Fig. 5 is a sectional elevation of the being continuously free from such contact. Thus nut with a spring member of another shape, and by r n in h sprin m mber d in such a Fig. 6 shows the spring member of Fig. 5 demanner and making it of such a shape that its tached, Fig, 7 is a, plan iew, part section, of tensioned and thread-contacting surfaces are at the nut with a second slot in the crown. Fig. 8 the. same distance from each other as the diawall of t crown the same time, the thread exerts at the point cording to this invention, for an ordinary nut. t e 0f he member d' until it conforms to The nut a is screw-threaded internally to conarcllate Shape Of a portion of the bolt form with the thread-of bolt e and is provided. d-

with a counterbored crown b which is shown of he prevention of the movement of the spring cone-frustum shape thus forming an undercut member 111 an upward dlrectloh a y m recess 6 for t prmg member d e crown the body of the nut a, together with the provisaid slot being shown parallel with the axis of Spring member, l ensure that the p g sur- At its top end, the edges of the slot are closed the Said action gradually increasing as each or brought towards one another to prevent the chord-like arm is mated by the b0? thread until said extremities d d from leaving the slot. e ptimum point is reached when all the sides The spring-member d is of non-drawer shape or arms of the spring member d are absorbed in and in Fig. 1 18 shown as square-shaped in plan. the th The internal diameter of the recess 0 is such as A sprmg member at of purely circular form will cause of t l of t crown. forded by an angular spring member of, for ex- Resistance is thus provided at the points of mp u a a triangular or square shape in round with the bolt or to move in a radial dithe pitch of the thread. rection is counteracted. The upper portion of As shown in Figs. 5 and 6, the spring member the crown b may be shaped from the cylindrical it may take the form of an oval or closed V, which is shaped to embrace and with two arms. to the wall of the substantially opposite to the slot the bolt e on opposite sides This member d is anchored recess in a bay 0 located b and the overlapping ends d d of the spring member. As contact with the bolt takes place, radial deformation of the two arms of the member d will take place to the arcuate form, whilst upward or outward movement of the member d is restricted by the bay 0 and the retaining slot N.

If desired, the cone-frustum crown b may be provided interiorly with one or more further bays or recesses in which the angles, corners or bends of the spring member d will be seated. Thus in Fig. '7, I have shown the square-shaped spring member d, with its superposed extremities cl d retained in slot W, with the opposite angle of the spring member (1 engagi'ngthe "sides of a second slot 1) extending from the 'top of 17 down to the body of the nut, and with the right andleft hand corners of the spring member engaging bays 0 in the wall of the crown b.

"In this Fig. '7; the spring member dis shown of square cross section whereas in Figs. 1 to 6 inelusive the member dis shown of round-section wire. In Fig. 8, the wire of the spring member is of triangular cross-section and the juxtaposed extremities are retained in a hole or aperture 12 through thewall of the cone-frustum crown b.

In the modification of Figs. 9 and 10, the invention is shown applied to a self-locking device suitable for use as an attachment to or in connection with an ordinary screw-threaded nut. The cone-frustum b is flatter or shallower than in the previous construction shown. The wall of b is inturned by flange f and is provided with a plurality of slots b b a four-armed spring member being housed in the chamber between flange f and wall 17.

The spring member (1 may be made of spring steel or rustless metals or of metals covered with fibrous materials. The cross-section of the spring wire may be of such shape as is desired, but the more it conforms with the shape of the thread to be mated,'the greater the area of frictional contact which will be effected.

' In place of the spring wire member shown, I mayemplo'y a split annular member which has been drawn, stamped or pressed to match the form of the bolt thread for which it is intended and of any suitable degree of flexibility.

What I claim is:

l. A safety nut comprising a body screwthreaded internally to engage with the thread of a screw, an annular chamber at one end of said body, and a spring member housed in said chamber, said spring member consisting of a single coil of non-circular shape having a helical pitch substantially equal to the pitch of said screwthread, the two extremities of said coil being anchored in a slot in a wall of said chamber, and intermediate portions of said coil providing resilient local contacts alternately with the interior'of said chamber and with the thread of the "projecting portion of a screw engaged in said body.

2. A safety nut comprising a body screwthr'eaded internally to engage with the thread of a screw, a crown upon one end of said body, said. crown providing an annular chamber substantially concentric with the screw-threaded interior of said body, and a spring member housed in said annular chamber, said spring member having overlapped 'ends and being of general polygonal shape and adapted to surround the projecting portion of a screw engaged in said body, the overlapped ends of said spring member being anchored to a wall of said chamber, polygon-angular portions of said spring member providing resilient local contacts with the interior of said chamber, and polygon-side portions of said spring member adapted to provide resilient local contacts with thethread of said projecting screw-portion. 3. A safety nut comprising a body, screwthreaded internally to engage with the thread of a screw, an annular chamber, at one end of said body, and aspring me ber housed insaid chamber, said spring member'being of substantially square configuration and adapted to surround the projectingportion of a screwenga'ged in said body, thefends of said spring member e ng br r a ps nd in a r d in a lo in the outer wall of said chamber, angular portions of, said spring member engaging tightly inbays in said wall, and side portions of said spring member adapted to provide resilient local contacts withth'e thread of said projecting screwpoirr ni- OHN se Q E SQ 

